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2016

DEPTH AND DEVELOPMENT OF THE SONIC SYSTEM IN DEEP- SEA MACROURID FISHES ON THE CONTINENTAL SLOPE

Jonothan Wrenn Virginia Commonwealth University

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DEPTH AND DEVELOPMENT OF THE SONIC SYSTEM IN DEEP-

SEA MACROURID FISHES ON THE CONTINENTAL SLOPE

A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science at Virginia Commonwealth University.

JONOTHAN BENNETT WRENN BACHELOR OF SCIENCE, VIRGINIA POLYTECHNIC INSTITUTE & STATE UNIVERSITY, 2009 MASTER OF SCIENCE, VIRGINIA COMMONWEALTH UNIVERSITY, 2016

Director: MICHAEL L FINE, PHD ASSOCIATE PROFESSOR, DEPARTMENT OF BIOLOGY

Virginia Commonwealth University Richmond, Virginia May, 2016

Acknowledgement

I would like to acknowledge several people who have been vital to my success.

First and foremost, I would like to thank Dr. Fine, whose support and encouragement has driven me to pursue my passion for aquatics. Secondly, I thank Jack Musick and Eric

Hilton from the Fish Museum of Virginia Institute of Marine Science for making fish available. I would also like to thank Larami Van Ness for providing anatomical drawings. I would like to thank Mrs. Kay Wrenn, my mother, who has taught me determination and provided advice and confidence during times of adversity. I would also like to thank my close friends and family for their belief, support, guidance and advice. Lastly, I would like to thank my committee members: Dr. Michael Fine, Dr. Jennifer Stewart, and Dr. Leigh

MacAllister.

Table of Contents

Page

Acknowledgements ...... iv

List of Tables ...... vii

List of Figures ...... viii

List of Abbreviations...... ix

Chapter

1 Introduction ……………………………………………………………………5

2 Materials and Methods ...... ………...8

3 Results ...... 10

Swimbladder ...... 11

Sonic Muscle ...... 11

Analyses of species ...... 12

4 Discussion ...... 15

Figures for Results ...... 17

Reference List ...... 38

Vita...... 41

List of Tables

Page

Table 1: List of head length, fish weight, and sex ratio ...... 17

Table 2: List of location, date of collection, coordinates, and depth ...... 18

Table 3: Regression equations for Nezumia bairdii ...... 19

Table 4: Regression equations for Coryphaenoides rupestris ...... 20

Table 5: Regression equations for Nezumia equalis ...... 21

List of Figures Page

Figure 1: Drawing of swimbladder and its structure………………… ………………….22

Figure 2: Relationship of fish weight and head length of all species ...... 23

Figure 3: Relationship of fish weight and head length of all species ...... 24

Figure 4: Swimbladder and sonic muscle analyses of Coelorhicus carminatus...... 25

Figure 5: Swimbladder and sonic muscle analyses of Nezumia bairdii...... 26

Figure 6: Swimbladder and sonic muscle analyses of Nezumia bairdii ...... 27

Figure 7: Swimbladder and sonic muscle analyses of Coryphaenoides rupestris ...... 28

Figure 8: Swimbladder and sonic muscle analyses of Nezumia equalis ...... 29

Figure 9: Drawing Swimbladder and sonic muscle analyses of Coryphaenoides armatus…………………………………………………..………………… ………………….30

Figure 10: Swimbladder and sonic muscle analyses of Coryphaenoides carapinus ...... 31

Figure 11: Swimbladder and sonic muscle somatic indices for all species ...... 32

Figure 12: Gonasomatic indices for Coelorhincus carminatus, Nezumia bairdii, and

Coryphanoides rupestris...... 33

Figure 13: Gonasomatic indices for Nezumia equalis, and Coryphanoides armatus and

Corpyhaenoides carapinus...... 34

Figure 14: ANCOVA of SBSI ...... 35

Figure 15: ANCOVA of SMSI ...... 36

Figure 16: ANCOVA of GSI ...... 37

List of Abbreviations

GSI: Gonasomatic Index

GWt: Gonad Weight

HL: Head Length

Hz: Hertz

SBL: Swimbladder Length

SBSI: Swimbladder Somatic Index

SBW: Swimbladder Width

SBWt: Swimbladder Weight

SML: Sonic Muscle Length

SMSI: Sonic Muscle Somatic Index

SMW: Sonic Muscle Width

SMWt: Sonic Muscle Weight

TL: Total Length

Wt: Total weight

Abstract

DEPTH AND DEVELOPMENT OF THE SONIC SYSTEM IN DEEP-SEA

MACROURID FISHES ON THE CONTINENTAL SLOPE

By Jonothan Bennett Wrenn, B.S.

A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Biology at Virginia Commonwealth University.

Virginia Commonwealth University, 2016

Major Advisor: Michael L. Fine Associate Professor and Graduate Director, Department of Biology

Work on sound production of deep-sea fishes has been limited to anatomy, and no sounds from identified species have been recorded on the continental slope. Here I examined the sonic muscles of six species in the family Macrouridae by depth

(Coelorhincus carminatus, Nezumia bairdii, Coryphaenoides rupestris, Nezumia equalis,

Coryphaenoides armatus, Coryphaenoides carapinus,). Due to increasingly limited food with depth, I hypothesized that sonic muscle development would decrease with depth.

Sonic muscles were intrinsic and occurred in males and females. Swimbladder and sonic muscle dimensions increased linearly with fish size, but there were no clear differences with depth suggesting sound production remains important in deeper species.

Introduction

Little research has been conducted on fish sound production in the deep sea.

Marshall (1967) described sonic anatomy of deep sea fish families Ophidiidae and

Macrouridae on the continental slope. He noted the presence of muscles on the swimbladder and suggested they function in sound production, but development of sonic muscles has not been quantified.

Fishes produce sounds through various mechanisms that evolved independently

(Ladich & Fine 2006; Fine & Parmentier 2015; Parmentier & Diogo 2006). The most common method of sound production in fishes utilizes superfast sonic muscles that deform the swimbladder (Skoglund 1961; Fine et al. 2001; Connaughton, Taylor & Fine 2000;

Connaughton 2004; Millot, Vandewalle & Parmentier 2011), which functions as the sound radiator (Fine and Parmentier 2015). Muscles can be either extrinsic, typically coming from the head, or intrinsic and attaching only the bladder. The swimbladder and position and contraction of sonic muscles control sound amplitude, frequency and directionality by its shape and movement (Fine et al. 2001). In oyster toadfish, a 200 Hz sonic-muscle contraction is translated to a 200 Hz fundamental frequency from bladder oscillations

(Ladich & Fine 2006; Nguyen, Parmentier & Fine 2008).

Sounds produced by slow sonic muscle contraction have been observed in carapid fish (Parmentier et al. 2006). In comparison to the 10 ms twitch exhibited by the toadfish

(Skoglund 1961; Fine et al. 2001), a carapid twitch requires 500 ms, and the muscle tetanizes around 10 Hz. The carapid swimbladder is comprised of three components: an

unattached anterior lip, a posterior part fused to the spinal column, and a flexible fenestra that connects the two. A swimbladder plate, a specialized epineural rib, couples with rapid movement of the anterior lip to excite the posterior region of the bladder (Parmentier et al

2006).The anterior portion of the swimbladder is pulled slowly toward the cranial region by sonic muscle contraction, after which the swimbladder is released and rapidly rebounds setting bladder and plate into vibration (Parmentier et al 2006).

A combination of these two, a fast muscle combined with a slow snap-back mechanism occurs in the genus Glaucosoma (Mok et al. 2011). The anterior swimbladder and fenestra are extended by fast muscles placing a tendon under strain. The stretched tendon in turn causes the bladder to snap back rapidly causing an intense sound upon relaxation. Sound is caused by a fast rebound of the tendon, similar to the slow muscle mechanism in carapids (Parmentier et al., 2006; Mok et al. 2011).

The family Macrouridae, grenadiers or rattails, is found in the order Gadiformes.

Ninety percent of macrourid species occur in the subfamily Macrourinae; other subfamilies include Bathygadinae, Macrouroidinae, and Trachyrincinae. The Macrouridae contains around 385 species within thirty-four genera (Iwamoto, 2008). The genera

Coryphaenoides, Coelorinchus, and Nezumia contain the greatest number of species. The presence of sonic muscles on the swimbladder suggests the ability for acoustic communication in the vast, barren, and dark environment. Females have heavier and stouter bodies than males (Marshall, 1962). The impacts of evolutionary adaption to heightened hydrostatic pressure and limited food resources are not known.

In this study I will describe and quantify swimbladder and sonic muscle development of six macrourids of varying depths from several hundred to 3,000 m. Due to decreasing food availability with depth (Gartner, 1997), I hypothesized that sonic muscle size will decrease with depth.

‘

Materials and Methods

Six species of macrourids were obtained from the fish museum of the Virginia

Institute of Marine Sciences (VIMS, Gloucester point, VA). Specimens were fixed in 10% formalin and maintained in 90% ethanol. Specimens came from depths ranging from 300 to 3000 m and were collected 80 – 350 km off the mid-Atlantic coast (except for one collection of Nezumia bairdii from the southern Greenland coast) from the late 1960s to early 1990s (Table 1, 2).

Fish were measured for total length (TL), head length (HL) and weighed. Head length was measured from the most anterior point of the snout to the most posterior opercular point. Swimbladders, sonic muscles and gonads were removed and placed in

0.9% NaCl solution to ensure uniform hydration before weighing in milligrams.

Smaller samples were taken from the sonic muscle and gonad, and cross sections were cut at 10 µm cryostat. The sex of individuals was determined microscopically or females were sexed externally by the presence of a cloacal opening behind the anus. Gonad and sonic muscle weights were regressed against fish weight and linear dimensions against

HL. HL was used in regression analysis because slender tails often break off or are damaged. Gonasomatic index (GSI), swimbladder somatic index (SBSI) and sonic muscle somatic index (SMSI) were calculated using:

In species for which males and females were present, I used analysis of covariance to determine sexual differences.

Results

See Table 1 and 2 for species examined and their collection depths. Species are listed in order of collection depth, and many of our samples were biased toward males.

Coelorhincus carminatus ranged from 43.1 to 70.6 cm HL and 16.1 to 85.4 g and included

10 males and 2 females. Nezumia bairdii ranged from 12.3 to 50.8 cm HL and from 1.2 to

29.5 g and included 55 males and 6 females. Coryphaenoides rupestris ranged from 52.3 to

98.1 cm HL and 57.7 to 240.7 g and included 14 males and 4 females. Nezumia equalis ranged from 32.2 to 48.5 cm HL and 17.7 to 33.5 and included 6 males and 5 females.

Coryphaenoides armatus ranged from 25.8 to 62.0 cm HL and 5.4 to 64.8 g and included

11 males. Coryphaenoides carapinus ranged from 40.9 to 56.7 cm HL and from 26.8 to

65.2 g and included 4 males.

All species appeared sexually monomorphic externally, and females were identified by the presence of an external cloacal opening found behind the anus. The relationship of weight to HL increased exponentially in all species (Fig. 2), and regressions formed a cluster with no obvious relationship between depth and relative weight (Fig. 3). For instance C. carminatus, the shallowest species, was lightest per unit weight, C. armatus one of the deeper species was at the lighter end, and C. carapinus, the deepest species, was in the middle of the distribution. These findings suggest that all species were robust and likely have somewhat similar abilities to swim and capture food. The shape of the swimbladder was similar in all species, and sonic muscle dimensions were not different between sexes although I say this with caution due to the small sample size of females.

Some specimens had been dissected previously or damaged during preservation. I kept these because of the small sample sizes for most species.

Swimbladder

The swimbladder has a single chamber covered with a white tunica externa in all species (Fig. 1). It is located below the third though fourteenth vertebrae and is attached to the ventral sides of vertebrae 3 through 12 on the dorsal midline where the swimbladder is rigid and slightly concave. It is also closely attached to the dorsolateral ribs. The dorsal edge is straight until it curves to a blunt tip at the rostral and caudal ends. The anterior surface of the swimbladder is blunt and rounded. The swimbladder is widest at the anterior region and tapers posteriorly. It is elliptical in cross section, and the lumen is wider than high. Each species has three long retia maribila of varying length that occur in pairs; they start on the anterior ventral surface and extend caudally to the approximate midpoint of the bladder. Marshall (1960) stated that retia length varies from 7 to 13 mm in fish from 140 to

2300 m in depth.

Swimbladders of all species increased in length, width, and weight with fish size

(Table 3, 4, 5; Fig. 4, 5, 7, 8, 9, 10). Swimbladders were not obviously sexually dimorphic, and their dimensions co-scattered on graphs.

Sonic Muscle

The sonic muscles of the six species appear similar and do not exhibit sexual differences (Table 3, 4, 5; Fig. 4, 6, 7, 8, 9, 10). The pair of sonic muscles is intrinsic and attaches to the dorsal and dorsolateral region of the anterior swimbladder (Fig. 1). Parallel

muscle fibers travel in the anterior to posterior direction. Muscles exhibited a reddish color.

Coelorhincus carminatus

Since there were only two females, we did not compare regressions of males and females although they appear to overlap. Swimbladder length and width increased linearly with HL, and swimbladder weight increased linearly with fish weight (Fig. 4). Similarly, sonic muscle dimensions increased linearly with fish size (Fig. 4).

Nezumia bairdii

Swim bladder length (SBL) and swim bladder width (SBW), increased linearly with HL, and swim bladder weight (SBWt) increased with fish weight in both males and females (Fig. 5). An analysis of covariance for both season and sex indicated no significant difference in either parameter (Table 3). A combined regression line is therefore presented

(Fig. 5).

Data for males and females overlapped between sexes and between summer and winter samples (ANCOVA: p > 0.05). Sonic muscle length (SML) did not change in specimens between 11 and 40 mm HL and then increased rapidly in larger fish. Therefore the two regions were fit with a separate linear regression. Sonic muscle width (SMW) increased with HL although the increase leveled off somewhat in fish above 30 mm HL.

Sonic muscle weight (SMWt) continued to increase at a linear rate with fish weight perhaps because of rapidly increasing sonic muscle length and more slowly increasing width (Fig. 6).

Gonad weight (GWt) increased with fish size although the increase leveled off somewhat in fish reaching 35 mm. A linear increase in larger fish began around 40 mm fish weight (FW) which corresponds with the increase of SML in larger individuals (Fig.

6).

Coryphaenoides rupestris

SBW increased linearly with HL (Fig. 7), and SBWt increased linearly with fish weight in both males and females (Fig. 7); data for both sexes were combined. An analysis of covariance for season determined no significant difference in SBW and SBWt (Table 4).

SBL increased linearly with HL and showed a significant difference between sexes (Fig.

7).

SML, SMW, and SMWt were larger in females than in males Fig. 7). However, although female sonic muscles weighed more than in males, the regression slope was lower (Fig. 7).

Nezumia equalis

SBL and SBW increased linearly with HL, and SBWt increased with fish weight in both males and females (Fig. 8). Data for males and females overlapped between sexes and between summer and winter samples. An analysis of covariance for both season and sex determined no significant difference in either parameter (Table 5). A combined regression lines is therefore presented (Fig. 8).

SML increased linearly with HL in males. Similarly SMW increased in males, but did not in the four larger females. SMWt was larger in females and had a significantly

higher elevation than males (F1, 8 = 0.09927, p < 0.0001) (Fig. 8). An analysis of covariance determined that SMW and SMWt showed a difference between males and females (Table 5). SMW of females was higher than in males and explains the low r2 for

SMWt (Fig. 8).

Coryphaenoides armatus

SBL and SBW increased linearly with HL in males, and SBWt increased linearly with fish weight. SML and SMW also increased linearly with HL and SMWt with fish weight (Fig. 9).

Coryphaenoides carapinus

SBL and SBW increased linearly with HL, and SBWt increased linearly with fish weight. SML and SMW also showed a linear increase with HL, and SMWt with FW (Fig.

10).

Somatic Indexes

Swimbladder somatic index showed a suggestive, but not statistically significant, increase in swimbladder weight per total weight (Fig. 14) as depth increased (F5, 12 = 0.09, p = 0.0965) .Sonic muscle somatic indexes showed a linear increase for all species (Fig.

11). An analysis of variance exhibited no difference among species (Fig. 15). No differences were found between sexes of each species except for C. rupestris (Fig. 19).

Gonasomatic indicies increased linearly for all species and both sexes (Fig. 12, 13).

Note there were only two individual females for C. carminatus. An analysis of variance showed no significant difference among species (Fig. 16).

Discussion

Macrourids are present in all oceans from subarctic to antarctic regions and make up one of the most important deep-sea fish families (Marshall & Iwamoto 1973). Of the approximately 300 species, 90% populate the continental slope zones between depths of

200 and 3000 m (Marshall 1965). While much of its distribution and biology has been examined (McLellan 1977, Geistdoerfer 1978, 1978–1979, Mauchline & Gordon 1984,

1985, 1986, Gordon & Duncan 1987, Merrett 1987, Gordon & Mauchline 1990), nothing is known about its sound production beyond Marshall’s description of sonic muscles.

(Marshall 1967) suggested they function in sound production, but development of sonic muscles had not been measured. To my knowledge, this study identifies sonic muscles in females for the first time suggesting that they likely are equally capable of sound production.

The macrourid swimbladder is an oblong oval shaped vessel which is covered with a tunica externa. A long anterior retia maribila on the ventral surface extends to the middle of the bladder. The swimbladder has a semicircular anterior end, the dorsal edge is straight and ventrally the bladder tapers to a blunt posterior tip. It attached dorsally to the spine from the third to twelfth rib in all species examined.

Body proportions were somewhat similar (Fig. 2, 3). Swimbladder length, width, and weight increased linearly in all species. Data suggest that swimbladders may increase in size with depth. Deep-sea macrourids exhibit zones of predation averaging 200 – 400 m that are segregated by depth and overlap during times of limited food availability.

Individuals were shown to invade predation boundaries of competing species when slope- fish biomass and production are maximal. They are opportunistic euryphagic consumers that navigate the water column hundreds of meters food allocation (Laptikhovsky, 2005;

Carrasson, 2002) which explain the increased swimbladder weight of deeper individuals.

Similar body proportions and a well developed swimbladder suggest that all species, regardless of depth, are active swimmers.

Despite limited food availability, macrourids’ sonic muscles did not decrease with depth nor were they larger in males. Sonic muscles were similar in all species by sex, season, and depth except for C. rupestris. They are intrinsic and attach to the anterior dorsolateral end of the swimbladder. Fibers travel in the anterior to posterior direction.

Although hypothesized, no sexual dimorphism existed in any species except C. rupestris. Dimensions of the swimbladder, sonic muscle, and gonad were similar for both sexes. Male specimens dominated each collection for unknown reasons.

The lack of obvious decrease in swimbladder and sonic muscle development with depth suggests that deeper species are active foragers (Laptikhovsky, 2005; Carrasson,

2002) and that sound production likely plays an important role in social and reproductive behavior of these species at depths to 3,000 m despite restricted food availability on the lower continental slope.

Results Figures

Table 1. Table listing the head length, fish weight, and sex ratio.

Species HL, mm Weight, g males females Coelorhincus carminatus 43.1 – 70.6 16.1 – 85.4 10 2 Nezumia bairdii 12.3 – 50.8 1.2 – 59.5 55 6 Coryphaenoides rupestris 52.3 – 98.1 57.7 – 240.7 14 4 Nezumia equalis 32.2 – 48.5 17.7 – 33.5 6 5 Coryphaenoides armatus 25.8 – 62.0 5.4 – 64.8 11 0 Coryphaenoides carapinus 40.9 – 56.7 26.8 – 65.2 4 0

Table 2. Table listing the location, date of collection, coordinates, and depth of macrourid species.

Species Location Date of Collection Latitude Longitude Depth Collected Coelorhincus carminatus Mid Atlantic Bight 8-May-80 36.32.5 N 74.40.1W 338-343 m Blake Plateau 22-Sept-80 29.10.1 N 75.59.4 W 424 m Nezumia bairdii Scotian Shelf 24-Jul-70 58.37.5 N 43.55.8 W 340-360 m Mid Atlantic Bight 3-Nov-91 39.50.86 N 71-25-10 W 560-591 m Mid Atlantic Bight 22-Aug-90 38.58 N 72-48 W 458-631 m Coryphaenoides rupestris - 15-Aug-69 39.27.12 N 71.54 W 810-1400m Nezumia equalis - 7-Sept-75 33.33.4 N 76.03.8 W 980-1000 m Coryphaenoides armatus Mid Atlantic Bight 25-Aug-91 38.22.07 N 72.52.69 W 2505-2540m Coryphaenoides carapinus Norfolk Canyon 13-Jul-79 36.37.8 74.05.5 W 3000 m

Table 3. Regression equations comparing swimbladder sonic structures against fish weight (Wt) and TL, coefficients of determination, and analysis of covariance in Nezumia bairdii SBL, swimbladder length; SBW, swimbladder width; SBWt, swimbladder weight; SML, sonic muscle length; SMW, sonic muscle width; SMWt, sonic muscle weight; GWt, gonad weight. Slopes Intercepts Reg. eqn. r2 F P F P SBL Y=-11.60+1.042X 0.9460 F1,51=1.8738 0.177 F1,52=1.5055 0.2254 SBW Y=-2.054+0.2991X 0.8504 F1,51=0.0089 0.9249 F1,52=0.1106 0.7408 SBWt Y=31.87+1.662X 0.9228 F1,51=1.0262 0.3158 F1,52=1.1947 0.2794 SML Y=2.201+0.1141X 0.2628 F1, 51=1.5759 0.2151 F1,51=9.7131 0.00298 SMW Y=0.5767+0.04957X 0.9264 F1,51=3.4757 0.0680 F1,52=0.6268 0.4321 SMWt Y=10.36+0.866X 0.8801 F1,50=1.6154E-4 0.9899 F1,51=0.5082 0.4792 GWt Y=-6.022+1.998X 0.9306 F1,50=0.1649 0.6864 F1,51=6.3674 0.01478

Table 4. Regression equations comparing swimbladder sonic structures against Wt and TL, coefficients of determination, and analysis of covariance in Coryphaenoides rupestris SBL, SBW, SBWt, SML, SMW, SMWt, and GWt.

Slopes Intercepts Male Reg. eqn. r2 F P F P SBL Y=-1.141+0.0929X 0.9149 F1,18=9.2940 0.006 - - SBW Y=-0.4083+0.078X 0.6763 F1,17=0.0728 0.7906 F1,18=1.0614 0.3165 SBWt Y=1.341+0.1788X 0.8241 F1,15=0.1103 0.7444 F1,16=1.3341 0.2650 SML Y=0.0928+0.0270X 0.4758 F1, 16=3.5469 0.0779 F1,17=83.076 <0.001 SMW Y=0.3130+0.0257X 0.9136 F1,17=7.6011 0.0135 - - SMWt Y=0.0744+0.0083X 0.8693 F1,14=5.1629 0.0394 - - GWt Y=-0.1403+0.035X 0.3757 F1,18=15.460 0.0009 - -

Table 5. Regression equations comparing swimbladder sonic structures against Wt and TL, coefficients of determination, and analysis of covariance in Nezumia equalis SBL, SBW, SBWt, SML, SMW, SMWt, and GWt.

Slopes Intercepts Male Reg. eqn. r2 F P F P SBL Y=-0.7282+0.066X 0.9661 F2,16=0.8758 0.4356 F2,18=0.3210 0.7232 SBW Y=-1.604+0.5206X 0.7036 F2,17=0.4586 0.4586 F2,19=0.9540 0.4029 SBWt Y=1.468+0.3257X 0.8355 F2,16=0.3859 0.686 F2,18=3.4788 0.0528 SML Y=1.855+0.2913X 0.9103 F2, 16=0.0096 0.9905 F2,18=0.0286 0.9718 SMW Y=1.262+0.2338X 0.8794 F2, 7=6.3658 0.0396 - - SMWt Y=0.3293+0.2798X 0.2572 F1, 7=0.3981 0.3981 F1, 8=69.540 <0.001 GWt Y=05900+0.1365X 0.8236 F1, 7=2.1293 0.1879 F1, 8=70.015 <0.001

Figure 1. Lateral, dorsal, and ventral views of the swimbladder, sonic muscle, tunica externa, and retia maribila for all species.

C. carminatus N. aegualus 35 90 80 p-value < 0.001 33 p-value = 0.0794 2 70 r = 0.9820 30 r2 = 0.8878 60 28 50 25 40 23 30

Fish Weight, g FishWeight, 20 20 10 18 0 15 40 45 50 55 60 65 70 75 30 33 35 38 40 43 45 48 50

N. bairdii C. armatus 60 60 55 p-value < 0.001 p-value < 0.001 50 r2 = 0.7529 2 45 50 r = 0.9855 40 35 40 30 25 30 20 Fish Weight, g FishWeight, 15 20 10 5 10 0 10 15 20 25 30 35 40 45 50 55 25 30 35 40 45 50 55 60 65

C. carapinus C. rupestris 70 250 65 p-value = 0.1473 60 225 p-value < 0.001 r2 = 0.9690 200 55 r2 = 0.9339 175 50 150 45 125 40 100 35 Fishg Weight, 75 30 50 25 25 20 50 55 60 65 70 75 80 85 90 95 100 40 42 44 46 48 50 52 54 56 58 60 Head Length, mm Head Length, mm

Figure 2. Relationship of fish weight and head length of all species.

Length-Weight Regression of all Species by Depth 250 C. carminatus 200 N. bairdii C. rupestris 150 N. aegualus C. armatus 100

C. carminatus Fishg Weight, 50

0 0 20 40 60 80 100 Head Length, mm

Figure 3. Relationship of head length and fish weight of all species.

35 C. carminatus 18 C. carminatus 17 Male 30 Male Female 25 Female 16 20 15 14 15 p-value < 0.0001 13 2 10 p-value < 0.0001 r = 0.9511 12 2 5

r = 0.9470 11

Swim Bladder Length, mm Length, Bladder Swim Sonic Muscle Length, mm Length, Muscle Sonic 0 10 40 42 44 46 48 50 52 43 44 45 46 47 48 49 50 51 52 Head Length, mm 3 Head Length, mm 8 7 6 2 5 4 3 p-value < 0.0001 1 p-value < 0.0001 2 r2 = 0.8921 r2 = 0.8469

1 MuscleSonic Width,mm Swim Bladder Width, mm Width, Bladder Swim 0 0 40 42 44 46 48 50 52 40 42 44 46 48 50 52 Head Length, mm Head Length, mm 175 50

150 40 125 30 100 75 20 50 p-value < 0.0001 10 p-value < 0.0001 25 2 2

Sonic Muscle Weight, mg Weight, Muscle Sonic r = 0.9558 Swim Bladder Weight, mg Weight, Bladder Swim r = 0.9375 0 0 12 16 20 24 28 32 36 10 15 20 25 30 35 Total Weight, g Total Weight, g

Figure 4. Relationship of SBL and SBW to HL , SBWt to Wt, SML and SBW to HL, and SMWt to Wt of Coelorhincus. carminatus.

N. bairdii 50 Male Female 40 P < 0.0001 30 r2 = 0.9466 20

10 Swimbladder Length, mm Length, Swimbladder 0 0 10 20 30 40 50 Head Length, mm 16 14 12 10 P < 0.0001 8 r2 = 0.8665 6 4

Swimbladder width, mm width, Swimbladder 2 0 0 10 20 30 40 50 Head Length 175 150 P < 0.0001 125 r2 = 0.8832 100 75 50

Swimbladder weight, g weight, Swimbladder 25 0 0 10 20 30 40 50 60 70 Fish Weight, g

Figure 5. Relationship of SBL and SBW to HL, and SBWt to Wt of Nezumia bairdii. 26

N. bairdii 30 200 N. bairdii Male < 40mm p-value = 0.9736 Male < 40mm 2 175 25 Male > 40mm r < 0.0001 Male > 40mm Female 150 Female 20 125 p-value < 0.0001 r2 = 0.9049 15 100 p-value < 0.0001 r2 = 0.4367 75 10 p-value = 0.0014 50 r2 = 0.4835 5 Weight, mg Gonad

25 Sonic Muscle Sonic mm Length, 0 0 10 20 30 40 50 0 10 20 30 40 50 60 70

4 100 Male Male 80 Female 3 Female 60 2 40

1 p-value < 0.0001 p-value < 0.0001 20 2

r2 = 0.9491 r = 0.9172

Sonic Muscle Sonic Width, mm Sonic Muscle Sonic Weight, mg 0 0 10 20 30 40 50 0 10 20 30 40 50 60 70 Head Length, mm Fish Weight, g

Figure 6. Relationship of SML and SMW to HL of N. bairdii. Relationship of SMWt and GWt to Wt of Nezumia bairdii.

C. rupestris 70 C. rupestris p-value < 0.0001 20 60 r2 = 0.9149 p-value = 0.0044 2 50 Male r = 0.4758 15 40 Female 30 10

20 p-value = 0.0011 Male p-value = 0.0218 2 5 2

10 r = 0.9449 Female r = 0.8656

Swim Bladder Length, mm Length, Bladder Swim Sonic Muscle Sonic mm Length, 0 0 40 50 60 70 80 90 40 50 60 70 80 90 Head Length, mm Head Length, mm

25 p-value = 0.0002 p-value < 0.0001 20 2 2 r = 0.7684 20 r = 0.9136 15 15

10 10

5 5 p-value = 0.0053 2

Sonic Muscle Sonic Width, mm r = 0.9465 Swim Bladder Width, mm Width, Bladder Swim 0 0 40 50 60 70 80 90 40 50 60 70 80 90 Head Length, mm Head Length, mm

60 400 p-value < 0.0001 2 p-value < 0.0001 r = 0.8598 2 55 r = 0.8693 300

200 50

p-value = 0.0714 100 45

r2 = 0.8623

Sonic Muscle Sonic Weight, mg Swim Bladder Weight, mg Weight, SwimBladder 0 40 0 50 100 150 200 250 60 80 100 120 140 160 180 200 Total Weight, g Total Weight, g

Figure 7. Relationship of SBL and SBW to HL, SBWt to Wt, SML and SBW to HL, and SMWt to Wt of Coryphaenoides rupestris.

N. equalis N. equalis 14 50 45 12 p-value < 0.0001 40 10 p-value < 0.0001 2 2 35 r = 0.9106 8 r = 0.9715 30 6 25 4 20 Male Male

2 15 Female SonicMuscle Length, mm

Swim Bladder Length, mg Length, Bladder Swim Female 0 10 30 32 34 36 38 40 42 44 46 48 50 30 35 40 45 50 Head Length, mm Head Length, mm

60 50 55 50 p-value < 0.0001 40 45 p-value = 0.0057 r2 = 0.8771 40 30 r2 = 0.8794 35 30 20 p-value = 0.5084 25 2

20 10 r = 0.1574 Sonic Muscle Sonic Width, mm Swim Bladder Width, mm Width, Bladder Swim 15 10 0 30 32 34 36 38 40 42 44 46 48 50 25 30 35 40 45 50 Head Length, mm Head Length, mm

450 50 p = 0.8135 440 2 p-value = 0.0004 40 r = 0.02161 430 r2 = 0.7753 420 30

410 20 400 p = 0.3045 2 10 r = 0.2572

390

SonicMuscle Weight, mg Swim Bladder Weight, mgWeight, SwimBladder 380 0 15 18 21 24 27 30 33 10 15 20 25 30 35 40 Total Weight, g Fish Weight, g

Figure 8. Relationship of SBL and SBW to HL, SBWt to Wt, SML and SBW to HL, and SMWt to Wt of Nezumia equalis.

C. armatus C. armatus 9 20 8 7 15 6 5 10 4 3 5 2

Sonic Muscle Sonic mm Length, Swim Bladder Length, mm Length, Bladder Swim 0 0 20 25 30 35 40 45 50 55 60 20 25 30 35 40 45 50 55 60 Head Length, mm Head Length, mm

10 3.5 8 3.0 2.5 6 2.0 4 1.5 1.0 2

0.5

Sonic Muscle Sonic Width, mm Swim Bladder Width, mm Width, Bladder Swim 0 0.0 20 25 30 35 40 45 50 55 60 25 30 35 40 45 50 55 60 Head Length, mm Head Length, mm

80 19 70 60 18 50 17 40 30 16 20 15

Sonic Muscle Sonic Weight, mg Swim Bladder Weight, mg Weight, Bladder Swim 0 14 0 5 10 15 20 25 30 35 40 45 50 55 60 65 0 10 20 30 40 50 60 Total Weight, g Total Weight, g

Figure 910. Relationship of SBL and SBW to HL, SBWt to Wt, SML and SBW to HL, and SMWt to Wt of male Coryphaenoides armatus.

32.5 C. carapinus 17.0 C. carapinus

30.0 16.5 16.0 27.5 15.5 25.0 15.0

22.5 14.5

Sonic Muscle Sonic mm Length, Swim Bladder Length, mm Length, Bladder Swim 20.0 14.0 40 45 50 55 60 65 40 45 50 55 60 65 Head Length, mm Head Length, mm

4.5 7

6 4.0

5 3.5

Sonic Muscle Sonic Width, mm Swim Bladder Width, mm Width, Bladder Swim 3.0 3 40 45 50 55 60 65 40.0 42.5 45.0 47.5 50.0 52.5 55.0 57.5 Head Length, mm Head Length, mm

55 8.50 8.25 50 8.00 45 7.75 7.50 40 7.25 7.00 35

6.75

Swim Bladder Weight, mgWeight, SwimBladder Muscle Sonic Weight, mg 30 6.50 20 30 40 50 60 20 25 30 35 40 45 50 55 60 65 Total Weight, g Total Weight, g

Figure 10. Relationship of SBL and SBW to HL, SBWt to Wt, SML and SBW to HL, and SMWt to Wt of male Coryphaenoides carapinus.

C. carminatus N. equalis

2.0 p-value < 0.0001 2.0 p-value = 0.002 2 r2 = 0.8880 r = 0.8032 1.8

1.5 1.6

1.4

SMSI, % SMSI, SMSI, % SMSI, 1.0 Male Female 1.2

1.0 10 20 30 40 15 20 25 30 35

N. bairdii C. armatus

1.6 p-value = 0.1356 2.0 p-value < 0.0001 r2 = 0.03798 r2 = 0.9284 1.4 1.5

1.2 1.0

SMSI, % SMSI, SMSI, % SMSI, 1.0 0.5

0.8 0.0 0 20 40 60 80 0 20 40 60

C. rupestris C. carapinus 2.5 1.4 p-value = 0.0004 p-value = 0.0103 r2 = 0.4890 r2 = 0.9796

1.3 2.0 SMSI, % SMSI, SMSI, % SMSI, 1.2 1.5

1.0 0 100 200 300 25 30 35 40 45 50 55 60 65 70 Fish Weight, g Fish Weight, g

Figure 11. Sonic muscle somatic Indexes (SMSI) for all species. 32

5 C. carminatus 5.0 p-value = 0.0004 C. carminatus 2 4 r = 0.8127 4.8

4.6 3

GSI, % GSI, 4.4 2 4.2 Female Male 1 4.0 12 16 20 24 28 32 36 25 30 35

3 N. bairdii 4 N. bairdii

2 3 GSI, % GSI, 1 2 p-value = 0.0002 p-value = 0.0006 r2 = 0.9752 r2 = 0.1997 0 1 0 10 20 30 40 50 60 0 10 20 30 40 50 60 70

7.5 C. rupestris 8 C. rupestris

7.0 7 6.5

GSI, % GSI, 6.0 6 p-value = 0.0193 p-value = 0.0052 5.5 2 r2 = 0.3330 r = 0.8851 5.0 5 0 50 100 150 200 250 100 125 150 175 200 225 Fish Weight, g Fish Weight, g

Figure 12. Gonasomatic Indexes (GSI) for males and females of Coelorhincus carminatus, Nezumia bairdii and Coryphaenoides rupestris. 33

10 N. equalis 8 N. equalis p-value = 0.0282 r2 = 0.7387 p-value = 0.0290 2

8 7 r = 0.8387 GSI, % GSI, 6 6 Male Female

4 15 20 25 30 35 5 20 25 30 35

C. carapinus 8 C. armatus 2.5 p-value < 0.0001 p-value = 0.1070 2 6 r2 = 0.8330 r = 0.7974 2.0

GSI, % GSI, GSI, % GSI, 1.5 2

0 1.0 0 10 20 30 40 50 60 20 30 40 50 60 70 Fish Weight, g Fish Weight, g

Figure 13. GSI for males and females of Nezumia equalis, and males of Coryphaenoides armatus and Coryphaenoides carapinus.

Swimbladder Somatic Index

Swimbladder Somatic Index, % Index, Somatic Swimbladder 0

N. bairdii N. equalis C. armatus C. rupestris C. carapinus C. carminatus

Figure 14. Swimbladder Somatic Index (SBSI) for all species.

Sonic Muscle Somatic Index for all Male Species 2.0

1.5

1.0

0.5

0.0 Sonic Muscle Sonic Somatic Index,%

N. bairdii N. equalis C. armatus C. rupestris C. carapinus C. carminatus Sonic Muscle Somatic Index for all Female Species 2.0

1.5

1.0

0.5

0.0 Sonic Muscle Sonic Somatic Index,%

N. bairdii N. equalis C. rupestris C. carminatus

Figure 15. ANCOVA results of SMSI for males and females of all species. 36

Gonasomatic Index for all Male Species 8

2 Gonasomatic Index, % GonasomaticIndex,

N. bairdii N. equalis C. armatus C. rupestris C. carapinus C. carminatus Gonasomatic Index for all Female Species 8

2 Gonasomatic Index, % GonasomaticIndex,

N. bairdii N. equalis C. rupestris C. carminatus

Figure 16. ANCOVA results of GSI for males and females of all species. 37

Reference List

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VITA

Jonothan Bennett Wrenn was born on September 20, 1987 in Clifton Forge, VA, and graduated from Alleghany High School, Covington, VA, in 2005. He received his

Bachelor of Science in Biological Sciences and Minor in Watershed Management from

Virginia Polytechnic Institute & State University, Blacksburg, VA, in 2009. Jonothan was an intern for the Center for Aquatic Technology Transfer of the National Forest Service before joining the Master of Science in Biology program at Virginia Commonwealth

University, Richmond, VA.